Implement autoloading of entities in unknown namespaces. Eg. MyNamespace::MyClass. The implementation is far from ideal, but for the timeline we have it is good enough. On a second iteration it could be improved a lot.

include/cling/Interpreter/InterpreterCallbacks.h

@@ -13,6 +13,7 @@
 
 namespace clang {
   class Decl;
+  class DeclContext;
   class LookupResult;
   class Scope;
 }
@@ -54,6 +55,15 @@ namespace cling {
     ///\returns true if a suitable declaration is found.
     ///
     virtual bool LookupUnqualified(clang::LookupResult& R, clang::Scope* S);
+
+    virtual bool FindExternalVisibleDeclsByName(const clang::DeclContext* DC,
+                                                clang::DeclarationName Name);
+
+    void UpdateWithNewDecls(const clang::DeclContext *DC, 
+                            clang::DeclarationName Name, 
+                            llvm::ArrayRef<clang::NamedDecl*> Decls) {
+      SetExternalVisibleDeclsForName(DC, Name, Decls);
+    }
   };
 
   /// \brief  This interface provides a way to observe the actions of the
@@ -78,6 +88,13 @@ namespace cling {
     ///\brief DynamicScopes only! Set to true only when evaluating dynamic expr.
     ///
     bool m_IsRuntime;
+  protected:
+    void UpdateWithNewDecls(const clang::DeclContext *DC, 
+                            clang::DeclarationName Name, 
+                            llvm::ArrayRef<clang::NamedDecl*> Decls) {
+      if (getInterpreterExternalSemaSource())
+        getInterpreterExternalSemaSource()->UpdateWithNewDecls(DC, Name, Decls);
+    }
   public:
     InterpreterCallbacks(Interpreter* interp,
                          InterpreterExternalSemaSource* IESS = 0);
@@ -95,6 +112,7 @@ namespace cling {
     /// \returns true if lookup result is found and should be used.
     ///
     virtual bool LookupObject(clang::LookupResult&, clang::Scope*);
+    virtual bool LookupObject(const clang::DeclContext*, clang::DeclarationName);
 
     ///\brief This callback is invoked whenever interpreter has committed new
     /// portion of declarations.
@@ -157,6 +175,9 @@ namespace cling {
       ~SymbolResolverCallback();
 
       bool LookupObject(clang::LookupResult& R, clang::Scope* S);
+      bool LookupObject(const clang::DeclContext*, clang::DeclarationName) {
+        return false;
+      }
       bool ShouldResolveAtRuntime(clang::LookupResult& R, clang::Scope* S);
     };
   } // end test

lib/Interpreter/Interpreter.cpp

@@ -914,6 +914,15 @@ namespace cling {
       getCI()->getModuleManager()
         ->setDeserializationListener(m_CallbackAdaptor);
     }
+
+    // FIXME: We should add a multiplexer in the ASTContext, too.
+    llvm::OwningPtr<ExternalASTSource> astContextExternalSource;
+    astContextExternalSource.reset(getSema().getExternalSource());
+    clang::ASTContext& Ctx = getSema().getASTContext();
+    // FIXME: This is a gross hack. We must make multiplexer in the astcontext,
+    // or a derived class that extends what we need.
+    Ctx.ExternalSource.take(); // FIXME: make sure we delete it.
+    Ctx.setExternalSource(astContextExternalSource);
   }
 
   clang::ASTDeserializationListener*

lib/Interpreter/InterpreterCallbacks.cpp

@@ -25,6 +25,16 @@ namespace cling {
     return false;
   }
 
+  bool 
+  InterpreterExternalSemaSource::FindExternalVisibleDeclsByName(
+                                                          const DeclContext* DC,
+                                                         DeclarationName Name) {
+    if (m_Callbacks)
+      return m_Callbacks->LookupObject(DC, Name);
+    
+    return false;
+  }
+
   InterpreterCallbacks::InterpreterCallbacks(Interpreter* interp,
                                              InterpreterExternalSemaSource* IESS)
     : m_Interpreter(interp),  m_SemaExternalSource(IESS), m_IsRuntime(false) {
@@ -45,6 +55,10 @@ namespace cling {
     return false;
   }
 
+  bool InterpreterCallbacks::LookupObject(const DeclContext*, DeclarationName) {
+    return false;
+  }
+
 } // end namespace cling
 
 // TODO: Make the build system in the testsuite aware how to build that class